NEET Physics Waves MCQs

A closed organ pipe and an open organ pipe have the same fundamental frequency. If the length of the closed pipe is 20 cm, and the speed of sound in air is 340 m/s, what is the length of the open pipe closest to the first overtone of the closed pipe?

Two organ pipes, open at both ends, have lengths of 0.5 m and 0.505 m. If the speed of sound in air is 340 m/s, what is the beat frequency they produce?

A sound wave of frequency 500 Hz is emitted by a stationary source. An observer moving towards the source with a constant speed hears a beat frequency of 5 Hz due to the Doppler effect and reflection of the sound from a wall behind the observer. If the speed of sound is 330 m/s, the speed of the observer is approximately:

Two sources S1 and S2, separated by a small distance, emit sound waves of frequencies 400 Hz and 402 Hz respectively. An observer moving along the line joining the sources hears beats. If the speed of sound is 340 m/s, what is the maximum speed of the observer for which beats are still heard?

A bat emitting ultrasonic sound of frequency $f_0$ flies directly towards a large, smooth wall with a velocity $v_s$. If the speed of sound in air is $v$, and the bat hears the reflected sound, what frequency $f'$ does it perceive?

Two trains A and B moving with speeds $v_A$ and $v_B$ respectively, approach each other. The frequency of the whistle of train A is $f_A$. What is the apparent frequency heard by a passenger in train B if the speed of sound in air is $v$? (Consider both trains moving towards each other along the same straight line)

A source of sound moves away from a stationary observer with a speed equal to the speed of sound. What frequency will the observer hear?

A sound source emits frequency $f_0$. An observer moves towards the source with velocity $v_o$ and then moves away with the same velocity. If the speed of sound is $v$, what is the difference in the observed frequencies in the two cases?

A sound source moves with a constant speed $v_s$ along a circle of radius $R$. An observer is situated at a distance much larger than $R$ in the plane of the circle. The maximum and minimum frequencies heard by the observer are $f_{max}$ and $f_{min}$ respectively. If $v$ is the speed of sound, what is the ratio $\frac{f_{max}}{f_{min}}$?

A closed organ pipe and an open organ pipe have the same fundamental frequency. What is the ratio of their lengths?